SKU: 74865379303

Water Shutter Assembly – Fits MerCruiser V6/V8 Engines (Replaces 807166A1, 807166A2)

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Description

Water Shutter Assembly – Fits MerCruiser V6/V8 Engines (Replaces 807166A1, 807166A2)Water Shutter Assembly Fits MerCruiser V6 V8 Engines (Replaces 807166A1, 807166A2) This water shutter assembly is designed for MerCruiser V6 and V8 sterndrive engines from 1996 to the present, including 4. 3L (262 CID), 5. 0L (305 CID), and 5. 7L (350 CID) models equipped with a two piece exhaust manifold. This component is a direct replacement for MerCruiser part numbers 807166A1, 807166A2, and the 807166A3 kit. It serves the critical function of

Water Shutter Assembly – Fits MerCruiser V6/V8 Engines (Replaces 807166A1, 807166A2)

This water shutter assembly is designed for MerCruiser V6 and V8 sterndrive engines from 1996 to the present, including 4.3L (262 CID), 5.0L (305 CID), and 5.7L (350 CID) models equipped with a two-piece exhaust manifold.

This component is a direct replacement for MerCruiser part numbers 807166A1, 807166A2, and the 807166A3 kit. It serves the critical function of preventing water from flowing back into the engine through the exhaust system, which can cause severe damage like engine hydrolock.

  • Installation Location: Mounts inside the exhaust Y-Pipe.
  • Engine Compatibility: Fits gasoline MerCruiser V6 & V8 engines (1996+).
  • Complete Kit: Includes the water shutter and two required grommets for a drop-in installation.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Brand Part Number Notes
MerCruiser 807166A1 Shutter
MerCruiser 807166A2 Shutter
MerCruiser 807166A3 Kit (includes shutter and grommets)

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Brand Model Rated HP Stroke Years OEM Part No. Notes
MerCruiser 4.3L V6 Various 4-Stroke 1996+ 807166A1/A2 With Gen+ engines and 2-piece manifold
MerCruiser V6 & V8 Various 4-Stroke 1996+ 807166A1 Gen+ with larger Y-pipe
MerCruiser Alpha/Bravo Various 4-Stroke 1996+ 807166A1 Must match Y-pipe model

Technical Specifications

Specification Value
Product Type Exhaust Water Shutter Assembly
Installation Y-Pipe
Fuel Type Gasoline
Connection Drop-in with grommets
Housing Material Rubber with steel rod
Housing Color Black
Fitting Type Drop-in
Other Technical Attributes Prevents water backflow into engine; failure can result in engine hydrolock

Package Contents

  • 1 x Water Shutter Assembly (Replaces 807166A1/807166A2)
  • 2 x Grommets (Replaces 25-8M0204688)

Installation Guide

  1. Safety First: Disconnect the boat's battery before beginning work on the engine or exhaust systems.
  2. Access the Y-Pipe: Locate and access the exhaust Y-pipe where the upper exhaust hoses connect. This may require removing other components.
  3. Remove Old Shutter: Carefully remove the old, failed water shutter and its grommets from within the Y-pipe.
  4. Clean the Surface: Thoroughly clean the mounting surfaces inside the Y-pipe to ensure a proper seal for the new grommets.
  5. Install New Grommets: Insert the two new grommets into the designated holes inside the Y-pipe.
  6. Install New Shutter: Carefully insert the pins of the new water shutter assembly into the grommets until it is securely seated.
  7. Verify Function: Ensure the shutter can swing open and closed freely without binding.
  8. Reassemble Exhaust: Reconnect any exhaust hoses or components that were removed for access.
  9. Final Check: Reconnect the battery. Start the engine and check for any exhaust or water leaks around the service area.

Troubleshooting & FAQ

How do I know if I need to replace my water shutter?

Common signs of a failed water shutter include a rattling noise from the exhaust, evidence of water in the engine oil, engine overheating, or difficulty starting. The most critical sign is finding water in the cylinders, which indicates engine hydrolock, a severe condition that a functioning shutter helps prevent.

What is the purpose of a water shutter?

It acts as a one-way valve located in your exhaust Y-pipe. It opens to let exhaust gases out when the engine is running and closes to prevent water from flowing back into the engine cylinders when the engine is off or when decelerating quickly.

What engines does this water shutter assembly fit?

It is designed for a wide range of MerCruiser V6 and V8 engines made from 1996 and onward, specifically those with "Gen+" (Generation Plus) architecture and a two-piece exhaust manifold. Always confirm your engine model and year before ordering.

Is this a single part or a complete kit?

This is a complete replacement assembly that includes one water shutter and a pair of new grommets required for a proper installation. This corresponds to what MerCruiser sells as kit 807166A3.

OEM vs. Aftermarket?

This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?

We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?

This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

  • Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
  • This product is an aftermarket replacement part and is not an OEM component.
  • Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

  • Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
  • Fast Global Shipping: Free delivery worldwide in 5–15 days.
  • Direct from Manufacturer: Competitive pricing without compromising quality.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 74865379303

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4.3 ★★★★★
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Product Reviews
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Christopher Stockton
Birmingham, US
★★★★★ 5
Worked as expected, good assortment
Size: 30 PCS
Used these to replace missing/broken body panel fasteners and they fit as expected. The assortment covered what I needed without having to buy multiple packs. Good quality for the price and handy to keep around if you work on vehicles.
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Reviewed in the United States on January 22, 2026
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J. ROST
Lowell, US
★★★★★ 5
Must have
Size: 200 PCS
If you have machines, you have to have these available. The old ones are reusable, most of the time, but when they aren't, you have these. They are of the same material and quality as OEM. Same size, of course, and the few I have used look factory.
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Reviewed in the United States on February 7, 2026
L
Verified Purchase
Luke
Los Angeles, US
★★★★★ 4
Replacement for those infamous fastener rivet clips.
Size: 200 PCS
Any one who rides or owns a ATV or UTV knows exactly how temperamental this clips can be, they work great when new but as soon as you take them out they never fit right again. This is why I purchased this kit and the clips are exactly the same as Polaris OEM clips. These clips fit into a 8.5mm or 0.3” hole, I’m not sure what other ATV/UTV these will work on but verify your hole size before purchasing. Kit includes 150 fastener rivet clips and 1 remover tool which is made of decent quality and will get the job done until you can purchaser a better removal tool.
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Reviewed in the United States on February 19, 2023
T
Verified Purchase
Tom J St Marie
Chelsea, US
★★★★★ 5
Perfect
Size: 200 PCS
Worked great on a 2024 Honda Rancher 420.
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Reviewed in the United States on April 26, 2026
C
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Charles Jenkins
Cuba, US
★★★★★ 5
They do exactly what they are needed for
Size: 200 PCS
Great for whatever and reasonable price
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Reviewed in the United States on April 12, 2026

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